A tuner that receives a digitally modulated signal inputs a signal to a demodulation device that demodulates a digitally modulated signal, and an I channel (in-phase component) and a Q channel (quadrature component) of the input signal may be inverted, preventing normal demodulation of the input signal as it is.
Therefore, techniques have been proposed for fixing the inversion within the demodulation device when the channels of the input signal are inverted (for instance, see Patent Literature 1 and Patent Literature 2). In particular, a technique to quickly detect channel inversion has been proposed in Patent Literature 2.